In recreational vehicles, it has been common to employ vents in the roof which are hinged at one side and are elevated by means of an arm connected to the vent cover and to the structure of the recreational vehicle. Typically a single operator arm includes an integral sector gear which mates with a worm gear operated by a hand knob. An example of such an operator is shown in U.S. Pat. No. 3,846,938. In that patent and in the references cited therein, a single operator arm is employed.
In larger size vents, it is essential that greater rigidity is required. This has been accomplished employing double arm operators which trasverse arcuate paths in a plane vertical or normal to the plane of the surface in which the vent is mounted in passing through the open edge of the edge hinge of the vent cover. Both operators commonly have a single worm gear which drives a pair of integral sector gears.
I have discovered that whenever larger sizes of vents, namely those having an area in the order of three square feet or larger are to be used not only must double operator arm arrangement be employed, but provision must be made to combat vibration of the vent cover under heavy wind loading. Further, provision must be made for effective transfer of the substantial wind load to the body of the recreational vehicle.